Efforts to reduce drug administration errors in the intensive care unit should be aimed at the risk factors we identified in this study. Especially, focusing on system differences between the two intensive care units (e.g., presence or absence of full-time specialized intensive care physicians, presence or absence of protocols for the preparation of all parenteral drugs) may help reduce suboptimal drug administration.

Aims To demonstrate an epidemiological method to assess predictors of prescribing errors. Methods A retrospective case-control study, comparing prescriptions with and without errors. Results Only prescriber and drug characteristics were associated with errors. Prescriber characteristics were medical specialty (e.g. orthopaedics: OR: 3.4, 95% CI 2.1, 5.4) and prescriber status (e.g. verbal orders transcribed by nursing staff: OR: 2.5, 95% CI 1.8, 3.6). Drug characteristics were dosage form (e.g. inhalation devices: OR: 4.1, 95% CI 2.6, 6.6), therapeutic area (e.g. gastrointestinal tract: OR: 1.7, 95% CI 1.2, 2.4) and continuation of preadmission treatment (Yes: OR: 1.7, 95% CI 1.3, 2.3). Conclusions Other hospitals could use our epidemiological framework to identify their own error predictors. Our ®ndings suggest a focus on speci®c prescribers, dosage forms and therapeutic areas. We also found that prescriptions originating from general practitioners involved errors and therefore, these should be checked when patients are hospitalized.